student topic 3 assessment statements - blank version

8/9/2019 STUDENT Topic 3 Assessment Statements - Blank Version

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Topic 3: The Chemistry of Life

1.Assessment Statement Response Campbell pages Sample Test Questions

3.1 Chemical elements and water: 2 hours

3.1.1 State that the most

frequently occurring

chemical elements inliving things are

hydrogen, oxygen,carbon, and nitrogen

Pg. 33 What element occurs in all proteins?

Nitrogen

3.1.2 State that a variety of

other elements areneeded by livingorganisms, including

sulfur, calcium,

phosphorus, iron, andsodium

Pg. 33

3.1.3 State one role for eachof the elements

mentioned in 3.1.2

The major roles of these elements can be foundthroughout the textbook.

IB says:Refer to the roles in plants, animals, and

prokaryotes

What role does sulfur play in living organisms?D. Component of proteins


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3.1.4 Draw and label a

diagram showing thestructure of water

molecules to show theirpolarity and hydrogenbond formation

Pg 47-48 Draw and label a diagram, etc.

3.1.5 Outline the thermal,cohesive, and solvent

properties of water

Pg. 48-52 Outline the thermal properties of water.

3.1.6 Explain the relationshipbetween the properties

of water and its uses in

living organisms as acoolant, medium for

metabolic reactions, and

transport medium.

Pg. 48-52

IB says:Limit the properties to those outlined in 3.1.5


3/17

3.2 Carbohydrates, lipids, and proteins: 2hrs

3.2.1 Distinguish betweenorganic and inorganic

compounds

Pg 58. Campbell defines organic compounds ascompounds containing carbon. IB disagrees with that

definition

IB says: Compounds containing carbon that are found inliving organisms (except hydrogen-carbonates,

carbonates, and oxides or carbon) are regarded asorganic.

3.2.2 Identify amino acids,

glucose, ribose andfatty acids from

diagrams showing theirstructure

Pg. 70-78

IB says: Specific names of amino acids and fatty acidsare not expected.


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3.2.3 List three examples

each ofmonosaccharides,

disaccharides, andpolysaccharides.

IB says: The examples used should be: glucose,galactose, and fructose; maltose, lactose, and sucrose;

and starch, glycogen, and cellulose.

3.2.4 State one function ofglucose, lactose, and

glycogen in animals,and of fructose, sucrose,

and cellulose in plants.

Pg. 70-72, does not include function of fructose

3.2.5 Outline the role ofcondensation and

hydrolysis in therelationships between

monosaccharides,

disaccharides andpolysaccharides;

between fatty acids,

glycerol andtriglycerides; andbetween amino acids

and polypeptides.

Pg. 68-69The relationships between condensation and hyrdrolysis

reactions and the formation and disassembly ofmacromolecules is discussed in general though not with

all the specific molecules at left.

Campbell uses the term dehydration reaction in someplaces instead of condensation. These terms refer to

the same thing.

IB says: This can be dealt with using equations withwords or chemical formulas.


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3.2.6 State three functions of

lipids

Pg. 76-77

IB says:Include energy storage and thermal insulation.

3.2.7 Compare the use of

carbohydrates andlipids in energy storage

Can be inferred from 70-76 May 2006 PM (SL)

7c. Describe why carbohydrates and lipids are used asenergy stores

(c) carbohydrates and lipids contain a lot of chemicalenergy;carbohydrates are readily used in cell respiration /

sugars are quick access energy

stores;lipid molecules contain about twice as much energy

as carbohydrates;complex

carbohydrates/polysaccharides/starch/glycogen are

also long term energy

stores;lipids are long term energy reserves;

complex

carbohydrates/polysaccharides/starch/glycogen andlipids are insoluble /

will not diffuse out of cells;

complexcarbohydrates/polysaccharides/starch/glycogen/lipid


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s do not contribute(significantly) to osmotic pressure;

complex

carbohydrates/polysaccharides/starch/glycogen canbe converted into

sugars by hydrolysis;carbohydrates and lipids burn cleaner than proteins /

do not yield N waste; [6 max]

(Plus up to [2] for quality)

3.3 DNA structure: 1 hour

3.3.1 Outline DNA

nucleotide structure interms of sugar

(deoxyribose), base,and phosphate.

Pg. 87

IB says: Chemical formulas and the purine/pyrimidinesubdivision are not required. Simple shapes can be used

to represent the component parts. Only the relativepositions are required.

3.3.2 State the names of thefour base pairs of DNA

Pg 88

3.3.3 Outline how DNAnucleotides are linked

together by covalentbonds into a single

strand

Pg 88IB says: Only the relative positions are required.


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3.3.4 Explain how a DNA

double helix is formedusing complementary

base pairing andhydrogen bonds.

Pg 88

3.3.5 Draw and label a simplediagram of the

molecular structure ofDNA

Can be inferred from pages 87 and 88.IB says:An extension of the diagram in 3.3.3 issufficient to show the complementary base pairs of A-T

and G-C held together by hydrogen bonds and the

sugar-phosphate backbones. The number of hydrogenbonds between pairs and details of purine/pyrimidines

are not required.


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3.4 DNA Replication: 1 hour

3.4.1 Explain DNAreplication in terms of

unwinding the doublehelix and separation of

the strands by helicase,

followed by theformation of new

complementary strandsby DNA polymerase.

Pg. 89Helicase and DNA polymerase are not mentioned until

pages 300-304 (Concept 16.2)IB says:It is not necessary to mention that there is more

than one DNA polymerase.

6 May 2009 PM

6b Explain the process of DNA replication. [8]

3.4.2 Explain the significance

of complementary basepairing in the

conservation of the basesequence of DNA

Pg. 89

3.4.3 State that DNAreplication is semi-

conservative

Pg. 299 2009 Specimen Paper

6. The diagram shows part of a molecule produced by

replication of DNA. What is the significance of the

shaded and the unshaded regions? (One strand isshaded and the complementary strand is unshaded)

A. The shaded parts are DNA and the unshaded partsare mRNA.

B. The shaded parts contain adenine and thymine and

the unshaded parts contain guanineand cytosine.


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C. The shaded part is a codon and unshaded part is an

anticodon.D. One of the parts has been newly synthesized and

the other was part of a pre-existingDNA molecule.

3.5 Transcription and Translation: 2 hours

3.5.1 Compare the structure

of RNA and DNA

Pg. 88

IB says:Limit this to the names of sugars, bases, and the

number of strands.

6 May 2009 PM

6a Distinguish between DNA and RNA [3]

3.5.2 Outline DNA

transcription in terms of

the formation of anRNA strand

complementary to theDNA strand by RNA

polymerase

Pg. 311-315 May 2006 PM (SL)

5. (a) Determine the strand of mRNA that is

transcribed from the DNA strand below.A T C C A G G T C A A G

[1](b) List three of the other molecules, apart from

mRNA, required for transcription.

[3]

5. (a) U A G G U C C A G U U C [1]

(b) DNA;

RNA polymerase;(ribose) nucleotides / ribonucleotides / RNA

nucleotides;


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transcription factors;nucleoside/ribonucleoside triphosphates;

Any two of the following: A / C / G / U; [3 max]

3.5.3 Describe the geneticcode in terms of codons

composed of triplets of

bases.

Pg 314

3.5.4 Explain the process of

translation, leading to

polypeptide formation.

Pg 320-324

IB says:Include the roles of messenger RNA (mRNA),transfer RNA (tRNA), codons, anticodons, ribosomesand amino acids.

2009 Specimen Paper

7. If mRNA has a codon CAU, what is thecorresponding anticodon on the tRNA molecule?

A. CATB. GUA

C. CAUD. GTA

3.5.5 Discuss the relationship

between one gene andone polypeptide.

Pg. 310

IB says: Originally, it was assumed that one gene wouldinvariably code for one polypeptide, but many

exceptions have been discovered.


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3.6 Enzymes: 2 hours

3.6.1 Define enzyme andactive site

Pg. 150

3.6.2 Explain enzyme-

substrate specificity

Pg. 152

IB says: The lock-and-key model can be used as a basisfor the explantion. Refer to the three dimensional

structure. The induced-fit model is not expected at SL.

4 May 2006 PM (SL)

4. (a) State why each step in a biochemical pathway

often requires a separate enzyme.[2]

4. (a) enzymes are specific for their substrate / lockand key model / energy requirementsfor reactions with substrates vary;

each step of the pathway is unique / differentsubstrate at each step;

finer control of metabolic pathways; [2]

3.6.3 Explain the effects of

temperature, pH, and

substrate concentration

on enzyme activity

Pg. 154

I did not find a mention in Campbell of how substrate

concentration affects enzyme activity.

8. Which graph shows the relationship between the

substrate concentration and the rate of an enzyme

controlled reaction?

May 2006 PM (SL)

4(b) Explain the effects of either changing

temperature or pH on enzyme activity.[3]

(b) Either, temperature: [3 max]each enzyme has an optimal temperature for its

maximum activity;


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(small) temperature increases result in increasedenzyme activity to a

point/optimum;

increase activity due to increased movement ofmolecules / increased kinetic

energy or conversely stated;temperature increases above the optimum causes

(progressive) loss of activity due

to denaturation/shape changes

or, pH: [3 max]each enzyme has an optimal pH for its maximum

activity;

as pH varies from optimal pH, enzyme activitydiminishes / becomes inhibited;

loss of activity is due to denaturation/shapechanges;

gain or loss of hydrogen ions distorts tertiary shapeof enzyme;

homeostatic mechanisms maintain optimal

conditions for enzyme activity; [3 max]Credit marking points above if illustrated by a

suitably annotated graph.

3.6.4 Define denaturation Pg 84

IB says:Refer only to heat and pH as agents.


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3.6.5 Explain the use of

lactase in theproduction of lactose-

free milk

Not discussed in Campbell.

3.7 Cell respiration: 2 hours

3.7.1 Define cell respiration Pg. 161Important: Campbell uses the term cellularrespiration to refer ONLY to aerobic respiration. IB

uses the term cell respiration to refer to both aerobic

and anaerobic respiration.

3.7.2 State that, in cell

respiration, glucose in

the cytoplasm is brokendown by glycolysis intopyruvate, with a small

yield of ATP.

Pg. 165


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3.7.3 Explain that, during

anaerobic respiration,pyruvate can be

converted in thecytoplasm into lactate,or ethanol and carbon

dioxide, with no furtheryield of ATP.

Pg. 175

IB says: Mention that ethanol and carbon dioxide are

produced in yeast, whereas lactate is produced in

humans.

3.7.4 Explain that, duringaerobic cell respiration,

pyruvate can be brokendown in the

mitochondria into

carbon dioxide andwater with a large yield

of ATP.

Pg. 168-174 2009 Specimen Paper

9. Humans can respire aerobically and anaerobically.Which are products of both aerobic cell respiration

and anaerobic cell respiration in humans?

A. pyruvate and ATPB. pyruvate and lactate

C. ATP and carbon dioxideD. lactate and carbon dioxide

3.8 Photosynthesis: 3 hours

3.8.1 State that photosynthesis involves

the conversion of light

energy into chemicalenergy.

Pg. 181


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3.8.2 State that light from the

Sun is composed of arange of wavelengths

(colours).

Pg. 186

IB says:Reference to actual wavelengths or frequencies

is not expected.

3.8.3 State that chlorophyll is

the main photosyntheticpigment.

Pg. 182

3.8.4 Outline the differencesin absorption of red,

blue, and green light bychlorophyll.

Pg. 187-188

IB says: Students should appreciate that pigments

absorb certain colors of light. The remaining colors of

light are reflected. It is not necessary to mention

wavelengths or the structure responsible for theabsorption.

3.8.5 State that light energy isused to produce ATP,

and to split water

molecules (photolysis)

to form oxygen andhydrogen.

Pg. 184-185

3.8.6 State that ATP and

hydrogen (derived fromthe photolysis of water)

are used to fix carbondioxide to make organic

molecules.

Pg. 184-185


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3.8.7 Explain that the rate of

photosynthesis can bemeasured directly by

the production ofoxygen or the uptake ofcarbon dioxide, or

indirectly by anincrease in biomass.

Not specifically discussed in Campbell.

IB says: The recall of details of specific experiments to

indicate that photosynthesis has occurred or to measure

the rate of photosynthesis is not expected.

May 2006 PM (SL)

7. (b) Explain how the rate of photosynthesis can bemeasured. [7]

(b) CO2 +H2O (CH2O)n + O2 / suitable

photosynthesis equation;amount of CO2 absorbed (per unit time) can be

measured;

measuring the increase of biomass (per unit time);O2 excretion (per unit time) can be measured;

methods for measuring the above:volume of O2 (bubbles) produced per unit time can

be measured;

dry mass can be weighed;increase in starch concentration in leaves (as

measured by iodine);use of pH indicator can monitor CO2 uptake in

water;the rate of photosynthesis measured is relative

because some of the CO2 is

produced by the plant internally through respiration;the rate of photosynthesis measured is relative

because some of the carbohydrates

are used internally by the plant for respiration; [7max]

3.8.8 Outline the effects oftemperature, light

intensity, and carbondioxide concentration

on the rate of

photosynthesis.

Not specifically discussed in Campbell 2009 Specimen Paper

5(b) Outline the role of chlorophyll and the effects of

temperature, light intensity and carbondioxide concentration on the rate of photosynthesis.

[6]


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(b) chlorophyll is composed of a number of pigments;absorb different colours of light;

mainly red and blue absorbed;

green light reflected;

temperature increases rate;up to a point where enzymes denature;

light intensity increases rate;up to a point where maximum absorbance can occur;

carbon dioxide increases rate;

up to a point where fixation is at a maximum; [6

max]

student topic 3 assessment statements - blank version

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